In the preservation of fruits by a canning or preserving process, the fruits must be first transported to a suitable processing plant where they are subjected to large amounts of heat to reduce the water content and increase the solids content and/or to have additional ingredients such as sugar and/or citric acid added thereto for the purpose of causing the pectin in the fruit to set up. Oftentimes in the cooking process, the batch of fruit is subjected to a partial vacuum so that the cooking temperature may be lowered and the evaporation of the water contained in the fruits accelerated. Such processes heretofore have resulted in the gases and liquids in the cells of the fruit being evolved so rapidly as to burst or explode the cell walls and thus to destroy the structural integrity of the fruit and with the individual pieces, if any, of the fruit in the ultimate product being indistinguishable one from the other.
In general, it has long been desired to maintain the structural integrity of at least a substantial portion of the fruit and also to maintain the original coloration of the fruit which is frequently destroyed during the above-referred-to cooking process.
Additionally, it is necessary to transport the fruit from the area where it is grown to the ultimate processing plant which in some instances can be many thousands of miles away from the area where the fruit is grown. Transporting the fruit over such distances presents extreme problems because in the time required to ship the fruit over such distances and at the temperatures which may be encountered during the shipment, the fruit tends to spoil, e.g. by rotting, by the commencement of fermentation, by compression, or by a combination of all three. Accordingly, it has been customary to ship the fruit from the point of growth to a local processing plant where the fruit is immediately frozen and packed into large drums preparatory to shipping it to the remote canning or preserving plant where as above pointed out the fruit is processed to reduce the water content to a required amount prior to the ultimate canning or bottling step.
The shipment of this water (which must ultimately be removed) over long distances is very expensive, not only due to its weight but due to the cost of the drums as well as the cost of the energy required to freeze the water prior to shipment, which energy is lost when the fruit is allowed to thaw at its ultimate destination at the canning or bottling plant.
Heretofore, any efforts to remove this water prior to shipment have resulted in destruction of the structural integrity of the fruit such that the resultant canned product was a mass of indistinguishable fruit pieces.
Research leading to the present invention indicated that this water, having sugar and the fruit flavor dissolved therein, is contained in closed cells having semi-permeable cell walls and/or between the cells and that the rate of diffusion of the water from the cells and/or from between the cells must be carefully controlled to prevent structural damage to the cell walls and/or the fruit itself.